Except for conventional flotage trapping devices which control flotage so that the flotage is kept away from the predetermined region, conventional flotage trapping devices for trapping flotage such as dust include the following techniques:
(1) a system in which an air is blown toward the flotage by a fan and the flotage is removed by a filter or a fiber,
(2) a system in which an air is blown toward the flotage by a fan and the flotage is collected by application of electric field,
(3) a system in which an air is blown toward the flotage by a fan and the flotage is removed by a filter or a fiber which is provided with electric field,
(4) a system in which an air is blown toward the flotage by a fan, the flotage is caused to be charged by ions and is captured by electrodes, and
(5) a system in which the flotage is captured by a mesh provided with an adhesive and the like.
Except for the system using an adhesive, in either one of the above-mentioned systems an air blower such as a fan is provided within a housing, air is blown toward the flotage and then the flotage is collected. Therefore, mainly the flotage is removed by a filter or fiber, or the flotage is caused to be charged by ions and then captured by electrodes provided with voltage.
In the conventional system (1) in which an air is blown toward the flotage by a fan and the flotage is removed by a filter or a fiber, since the fan generates an air flow or wind and thus the flotage flies high in the air, the system is adversely harmful as a measure for removing the dust. In the system air is inevitably taken in within a housing of a dust collecting device or flotage trapping device and then an airborne dust is trapped. For this reason a big dust collecting device cannot be installed. Since the resistance of filter or fiber is big, the speed of wind cannot be increased and thus processing power is limited. For example, a long time operation is required to trap the dust as a whole in a large space. Furthermore, the fan which blows wind toward a dense filter needs a considerable degree of wind pressure. Therefore there are problems in that consumed power increases and running cost is expensive.
FIG. 31 shows a conventional system (2) in which a fan blow a wind toward the dust and the dust is collected by electric field. Since the fan generates an air flow or wind and thus the flotage flies high in the air, the system is adversely harmful as a measure for removing the dust. In the system air is inevitably taken in within a housing of a dust collecting device or flotage trapping device and then an airborne dust is trapped. For this reason a big dust collecting device cannot be installed. Since the air is blown slowly so that the electric field system works effectively, the speed of wind cannot be increased and thus processing power is limited. For example, a long time operation is required to trap the dust as a whole in a large space.
The dust collecting device for use in the system shown in FIG. 31 will be explained in more detail. The dust collecting device 1 or flotage trapping device includes a housing 8. Plate-like electrodes 10 are provided at the walls of the housing. That is, a plus or positive electrode 10a which is fed by a power supply 20 so as to be positively charged and minus or negative electrodes 10b which are fed by a power supply 20 so as to be negatively charged are disposed in juxtaposition. The electric flux lines 14 come out from the plus electrode 10a and are terminated at the minus electrodes 10b in a direction as shown by arrows. Within the housing 8, a fan 22 is disposed at the downstream of the electrodes 10a and 10b, and as shown by arrows 18 an air blow is flown from the upstream to the downstream. Assumed that the dust (plus dust 12a charged with plus electricity, minus dust 12b charged with minus electricity, and dust 12c without charge) exists at the upstream of the dust collecting device.
Now, when the fan is operated, the upstream dust is attracted toward the housing as shown in arrows 16 and is moved downstream between the plus electrode 10a and the minus electrodes 10b. At that time the plus dust 12a and minus dust 12b are respectively trapped or captured by the electrodes of opposite polarities. However, the dust 12c without charge is not trapped and thus moved downstream.
FIG. 32 shows the conventional system (3) in which a wind is blown by a fan toward the dust and the dust is removed by a filter or fiber provided with electric field. Since in the system the fan blows a wind, the dust flies high and thus the system is adversely harmful as a measure for dust. In the system air is inevitably taken in within a housing of a dust collecting device or flotage trapping device and then an airborne dust is trapped. For this reason a big dust collecting device cannot be installed. Since the resistance of filter or fiber is big, the speed of wind cannot be increased and thus processing power is limited. For example, a long time operation is required to trap the dust as a whole in a large space.
Furthermore, since the filter is provided with electrodes, this filter other than a simple filter without electrode is expensive, and the running cost for exchange of filter is added. Furthermore the fan which blows a wind toward a dense filter needs a considerable degree of wind pressure. Therefore there are problems in that consumed power increases and running cost is expensive.
The dust collecting device using the system as shown in FIG. 32 will be explained in more detail. The dust collecting device comprises a housing 8. Within the housing, a mesh-like high voltage electrode 10, plus electrode 10a in the embodiment, is provided inside a filter or fiber 24 and a grounded electrode 10c is provided on the surfaces of the fiber 24 opposed to the electrode 10a. Furthermore, within the housing, a fan 22 is disposed at the downstream of the fiber 24 with electrode and air blow is adapted to flow from the upstream to the downstream as shown by arrows 18.
Now, when the fan 22 is operated the upstream dust is sucked in within the housing as shown by arrows 16 and is passed through the fiber 24 with electrode. The charged dust is captured by polarized fiber and electrode, and non-charged dust is captured by the fiber.
FIG. 33 shows a conventional system (4) in which a wind is blown by a fan, the flotage such as dust is caused to be charged by ions and captured by electrodes. Since the fan generates an air flow or wind and thus the flotage flies high in the air, the system is adversely harmful as a measure for removing the dust. In the system air is inevitably taken in within a housing of a dust collecting device or flotage trapping device and then an airborne dust is trapped. For this reason a big dust collecting device cannot be installed. Since the air is blown slowly so that the electric field system works effectively, the speed of wind cannot be increased and thus processing power is limited. For example, a long time operation is required to trap the dust as a whole in a large space.
The dust collecting device using the system as shown in FIG. 33 will be explained in more detail. The dust collecting device 1 comprises a housing 8. The electrodes, plus hollow cylindrical electrodes 10a in the embodiment, which are grounded or are fed by a power supply 20 are disposed on the wall of the housing 8 opposite to each other. Within the housing 8, a discharge needle 26 fed by the power supply 20 is provided at the upstream of the electrodes 10 so as to issue minus ions 28b toward the upstream, and a fan is disposed at the downstream of the electrodes 10, and thus air blow is adapted to flow from the upstream to the downstream as shown by arrows 18.
Now, when the fan 22 is operated, the upstream dust 12 is sucked in within the housing 8 as shown by arrows 16, and within the housing the dust is caused to be charged with minus electricity by the minus ions 28b. The dust is attracted by the plus electrodes 10a and captured by the electrodes 10c or 10a. 
In the conventional system (5) in which the dust is captured by attachment to a mesh coated with adhesive, due to the function of capturing the attached dust, the capture depends on accidental attachment to fine threads of the mesh. Its capture efficiency is very low compared with forcible capture as made by other systems.
Therefore, it is an object of the present invention to provide a flotage trapping or capturing device which can capture the flotage such as dust in a simple construction and is not expensive.
It is another object of the present invention to provide a flotage repelling device which can repel the flotage such as dust in a simple construction and is not expensive.